Impact-operated electric switch with variable sensitivity



Oct. 14, 1 969 a. WINTRISS 3,472,979

IMPACT-OPERATED ELECTRIC SWITCH WITH VARIABLE SENSITIVITY Filed Nov. 6. 1967 'l 94 Ii i H '6 II I I /-/O I I- l i i 90 92 0 l 74 e 3 74b 6c 740' u 42 -44 O 50 6O 52 INVENTOR W WNW N M.

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ATTORNEYS.

United States Patent 3,472,979 IMPACT-OPERATED ELECTRIC SWITCH WITH VARIABLE SENSITIVITY George Wintriss, Carversville, Pa., assignor to Industrionics Controls, Inc., New York, N.Y., a corporation of New York Filed Nov. 6, 1967, Ser. No. 680,878 Int. Cl. H01h 35/02 U.S. Cl. ZOO-61.45 Claims I ABSTRACT OF THE DISCLOSURE This specification discloses an electric switch that is responsive to impacts against its housing. Springs that move contacts of the switch in one direction act against the force of fluid pressure in a chamber behind a flexible diaphragm, and the sensitivity of the switch, i.e., the force of impact required to operate it, depends upon the pressure of the fluid behind the diaphragm. By changing the pressure opposing the springs, and without making any structural changes in the switch, it can be made to operate in response to light or heavy impacts, depending upon the intended service. The switch has a movable contact connected to the diaphragm by means that extend through the diaphragm. A second imperforate diaphragm covers the connecting means on the pressure-chamber side.

Cross references to related applications Some of my earlier electric switches having inertia elements and adapted to be operated in response to the striking of the switch housing, or connected structure, by a work piece, are disclosed in US. Patents 3,256,397, issued June 14, 1966; 3,263,039, issued July 26, 1966; and in my allowed application Ser. No. 444,360; filed Mar. 31, 1965.

In all of these constructions the switch is held in its normal position by either a magnet or by spring pressure. In order to change the sensitivity of the switch, for operation by the impact of heavier or lighter work Pieces, it was necessary to change the spring or magnet; and this was inconvenient because it required return of the apparatus to the factory; and it was impractical for units constructed with permanent closures.

With the present invention, a different type of switch is used, of the general type shown in my co-pending applications Ser. No. 610,652, filed Jan. 20, 196-7; Ser. No. 623,252, filed Mar. 15, 1967; and Ser. No. 637,411, filed May 10, 1967.

An inertia element is added to the switch above a flexible diaphragm and variations in pressure under the diaphragm are used to adapt the switch to operation by impact of work pieces of different size, weight, or velocity of impact.

Background and summary of the invention This invention provides an impact-operated electric switch that has its contacts held in closed position by fluid pressure which can be changed to make the switch operation more sensitive or less sensitive to the impact of work pieces that strike the switch housing, or connected structure, as they are discharged from an automatic machine. The preferred construction connects the inertia element to a flexible diaphragm and applies gas pressure to the side of the diaphragm opposite to that on which the inertia element is located. The gas pressure in the chamber behind the diaphragm is adjusted by means of a pressure regulator. The principal object of this invention is to provide an impact-operated electric switch, the sensitivity of which is variable as desired. This permits a substantial degree of standardization of such switches. A highly sensitive switch 3,472,979 Patented Oct. 14, 1969 is necessary on some machines that make light work pieces; but the same sensitivity on a larger and heavier machine may result in false signal pulses caused by vibrations of the machine itself. Even with the same machine operating on light work, high sensitivity may be necessary; but when operating on heavy stock, the machine may be subject to vibrations that will actuate an impact switch of the sensitivity necessary for the light work pieces.

Another advantage of having an impact switch that can be adjusted for sensitivity on the job is that impact is a dynamic phenomenon and it is difficult to compute the sensitivity necessary for a machine in a factory remote from the switch manufacturers shop.

Another object of the invention is to provide an impact switch of inexpensive construction and which is suitable for long use without attention. Features directed to this object include a double diaphragm construction for sealing the connection of the inertia element to the diaphragm; the connection of a power cable with the contacts of the switch; and a construction that produces wiping action of the switch contacts so that they remain clean and smooth indefinitely.

Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.

Brief description of the drawing In the drawing, forming a part hereof, in which like reference characters indicate corresponding parts in all the views:

FIGURE 1 is a sectional view of an impact-operated electric switch made in accordance with this invention; and

FIGURES 2 and 3 are sectional views, on a reduced scale, taken on the lines 22 and 3-3 of FIGURE 1.

Description of the preferred embodiment The impact-operated switch shown in the drawing includes a housing 10 having a cover 12 which fits into a socket 14-at the upper end of the housing. After the switch has been assembled and the cover 12 has been inserted into the socket 14, an upper edge portion 16 of the housing is rolled over to lock the cover 12 permanently in place. A sealing ring 18 is preferably provided between the upper edge portion 16 and the cover 12 t0 hermetically seal the inside of the housing 10.

Conductors 21 and 22 extend from within the cover 12 through an outlet 24 at the top and center of the cover 12. After the switch has been assembled, the space around the conductors 21 and 22 and the outlet 24 is sealed by potting 26 and the upper edge 28 of the outlet 24 is preferably rolled over before the potting 26 hardens. This locks the potting in the outlet 24.

Within the housing 10 there is a chamber having a sloping bottom 30 which meets with an annular shoulder 32. This shoulder 32 is shown with two levels, the upper one of which has a circumferential ridge 34. There are two diaphragms 36 and 38 with their circumferential portions supported by the shoulder 32. The lower diaphragm 36 is a thin, imperforate diaphragm for the purpose of preventing leakage through the connection of the upper diaphragm 38 with a block 40 which serves as an inertia element for the switch. The lower end of this inertia element 40 is connected with the diaphragm 38 by a rivet 42 which is shown in the drawing as being of one-piece construction with the rest of the block 40. However, this rivet 42 is merely representative of fastening means for securing the center of the block 40 to the upper diaphragm 38.

The diaphragm 38 is flexible and may be made of rubber, neoprene, or the like. The lower diaphragm 36 can be made of the same material but it is much thinner and can be flexible to the degree of being limp, since its function is to seal the rivet opening at the center of the diaphragm 38, and to seal any clearance between the peripheral portion of the diaphragm 38 and the chamber wall which extends upward from the shoulder 32. The ridge 34 provides high unit pressure between the shoulder 32 and the diaphragm 36 so that no fluid can escape under the diaphragm 36 to the periphery of the shoulder 32.

The diaphragms 36 and 38 divide the interior of the housing into diflerent chambers including a chamber 44 below the diaphragms. Fluid is supplied to the chamber 44 through a passage 46 which opens into a counterbore 48 having threads 50 for receiving a fitting that connects the passage 46 with a pressure regulator 52. Fluid under pressure, preferably compressed air, is supplied to the pressure regulator 52 from a compressed air source and through a conduit 54. The pressure regulator has an adjustment 56 which can be changed to regulate the delivery or downstream pressure; and the downstream side of the regulator 52 is connected with the passage 46 through a conduit 60. A pressure gauge 62 indicates the downstream pressure and the pressure in the lower chamber 44 of the housing 10.

The diaphragms 36 and 38 are clamped against the shoulder 32 by a sleeve 66. The interior of this sleeve 66 provides a chamber for the block 40. Except for its center connection with the diaphragm 38, the block 40 is not otherwise connected with the diaphragm 38 and it is loose in the sleeve 66. Thus the block 40 can shift transversely and move into canted positions with respect to its longitudinal axis to the limited extent that the flexing and warping of the diaphragm 38 permits such movement. The block 40 is a conductor of electricity and is preferably made of aluminum. It is large enough to have a substantial amount of inertia, and this is important because the switch is operated in response to the inertia of the block 40.

The sleeve 66 is held down, in clamping relation with the diaphragms 36 and 38, by a frame 68 which is preferably made of electrical insulating material. This frame 68 is the contact holder for the fixed contacts of the switch and it is of circular cross section with its lower part of a diameter to fit the interior of the housing 18 just above the sleeve 66. The diameter of the frame 68 decreases at a shoulder 70 and then continues to extend upward to form a stud 72, a part of the length of which is hollow.

There are three openings through the large diameter portion of the frame 68. These openings are preferably of circular cross section and they are indicated in FIG- URE 3 by the reference characters 74, and 76. In the construction illustrated, the openings 74, 75 and 76 are at 120 spacing around the longitudinal axis of the frame 68. Both of the openings 74 and 76 are shown in FIGURE 1 by taking the section of FIGURE 1 along a broken plane, as indicated by the section line 11 in FIGURE 3.

A switch contact 74a fits into the opening 74 with a press fit. This switch contact 74a is made of electrically conductive material but preferably has an insert 74b in its bottom face to improve the wearing quality of the contact 74a. Silver can be used for the insert 74b, but a silver tungsten alloy is preferred. A similar complementary insert 74c is pressed into a socket in the block 40 for contact with the insert 74b when the block 40 is raised to close the switch.

There is a switch contact 76a in the opening 76 and this contact 76a preferably fits the opening with a press fit and is similar in construction to the contact 74a, already described. An insert 76b contacts with an insert 760 in the block 40.

There is a contact 75a (FIGURE 3) which fits into the opening 75 with a press fit; but this contact 75a is preferably not a conducting contact of the switch and is used to provide the stability of three-point support for the block 40 (FIGURE 1) when the block 40 is thrust upward to close the switch. The contact 75a is made of electrical insulating material.

A helical spring 80 surrounds the stud 72 and contacts at its lower end with the top surface of the switch contact 74a. The upper end of the spring 80 abuts against an insulator 82 which fits into the upper part of the housing 10. A portion of the top convolution of the spring 86 contacts with bare wires 84 of the conductor 22. A sleeve 86 of electrical insulating material surrounds the outside of the spring 80.

Another helical spring 90 surrounds the sleeve 86. The lower end of the spring 90 contacts with the top surface of the switch contact 76a. A sheet of insulation 92 prevents the spring 90 from touching the switch contact 74a. The upper convolution of the spring 90 contacts with the insulator 82 around part of the circumferential extent of the spring, and contacts with bare wires 94, of the conductor 21, around another part of the circumferential extent of the spring. Thus the springs 80 and 90 serve as conductors for connecting the switch contacts 74a and 76a, respectively, with the conductors 22 and 21, respectively.

In the operation of the apparatus, the housing 10 is located in the path of work pieces which are discharged from an automatic machine, or the housing is connected with a deflector plate which is located in the path of work pieces discharged from the machine. As the result of impact of the work piece with the housing 10, or structure connected with and forming, in effect, a part of the housing 10, the housing is jarred. The block 40, being loose in the housing, except for its connection with the flexible diaphragm 38, is less affected by the impact than is the housing. There is, therefore, a relative movement between the housing and the block 40. Since the switch contacts 74a and 76a are rigidly assembled with the housing 10, there is relative movement between these switch contacts and the block 40. If this relative move ment is sufiicient, the switch is opened by separation of the inserts 76b and 76c from one another; and with somewhat greater movement, the inserts 74b and 740 are separated from one another.

The degree of impact necessary to open the switch depends upon the pressure of the fluid in the chamber 44 under the diaphragms 36 and 38. Thus the sensitivity of the switch can be changed by adjusting the downstream pressure of the regulator 52. This represents a radical departure from past impact sensor concepts. In practice, the sensitivity can be varied from extreme sensitivity (the free fall of a Ms" ball over a distance of less than /2") to a sensitivity suited for larger and heavier parts (the impact of a A" ball falling freely over a distance of three inches or higher). It also permits setting of sensitivity in the field to suit exact requirements. One of the advantages of adjusting the sensitivity so that it is no greater than necessary is that it permits scrap to be ignored whenever its ejection might coincide with the time when a part is to be ejected. Increasing the pressure in the chamber 44 decreases the sensitivity of the impact-responsive switch of this invention.

In the switch construction illustrated, the contact inserts 74b and 740 are closer together than are the contact inserts 76b and 760 when the block 40 is moved away from the contact holder frame 68. When the block 40 is moved upward in FIGURE 1, the contact inserts 74b and 740 touch each other while the contact inserts 76b and 760 are still spaced from one another. Thus the movement of the block 40 is stopped on one side and the continued displacement produces a gyration of the block. The momentum remaining when the contacts touch, causes the contacts to have a limited lateral sliding movement which produces a wiping action for maintaining the contacts in clean condition.

The preferred embodiment of the invention has been illustrated and described, but changes and modifications can be made and some features can be used in different combinations without departing from the invention as defined in the claims.

What is claimed is:

1. An impact-operated electric switch including a housing, an inertia element in the housing, switch contacts in the housing including at least one contact on the inertia element and movable toward and from another of the switch contacts in response to relative movement of the inertia element and the housing, means holding the contact on the inertia element against the other contact including a pressure chamber having a movable wall, means for supplying difierent degrees of fluid pressure to the chamber and against said wall to change the sensitivity of the switch to impacts of different magnitude, the pressure chamber being on the side of the inertia element remote from the electric contacts, and the pressure in said chamber urging the inertia element and its electric contact toward the other electric contact.

2. The impact-operated electric switch described in claim 1 characterized by the moveable wall of the pressure chamber being a flexible diaphragm, and the inertia element being mechanically connected to the flexible diaphragm.

3. The impact-operated electric switch described in claim 2 characterized by the inertia element being mechanically connected to the flexible diaphragm near the center of the diaphragm and having a limited universal movement within the limits of the warping of the flexible diaphragm.

4. The impact-operated electric switch described in claim 2 characterized by the flexible diaphragm having a center opening, a retainer extending from the inertia element through the diaphragm to the other side thereof and having a head of the retainer on said other side of the diaphragm securing the inertia element to the diaphragm, and a second flexible diaphragm thinner than the first diaphragm and extending across the head and the surrounding area of the first diaphragm to seal the chamber against leakage of gas between the retainer and the edges of the opening in the first diaphragm.

5. The impact-operated electric switch described in claim 4 characterized by the pressure chamber having a shoulder around the periphery thereof, a cylindrical sleeve in the housing on the other side of the diaphragms from said shoulder, both of the diaphragms having their peripheral edge portions clamped between the sleeve and the shoulder, the inertia element being generally cylindrical and of an outside diameter less than the inside diameter of the sleeve, and structure in the housing holding the sleeve down in its clamping position.

6. The impact-operated electric switch described in claim 5 characterized by contact holders that press against the end of the sleeve remote from the diaphragms, two relatively fixed electric contacts on the contact holders and confronting the inertia element, two electric con-" tacts on the inertia element in position to touch the contacts of said contact holders, spring means urging the contact holders against the sleeve, and a cover on the housing compressing the spring means.

7. The impact-operated electric switch described in claim 6 characterized by the spring means including a different coil spring in contact with each of the relatively fixed contacts, and an electric cable that enters the end of the housing remote from the diaphragms and that has two conductors, a different one of said conductors being in contact with each of the coil springs.

8. The impact-operated electric switch described in claim 2 characterized by the inertia element having at least two switch contacts carried thereby, and there being at least two other switch contacts that are relatively fixed and that are touched by the inertia element switch contacts when there is gas pressure behind the diaphragm, the inertia element having at least a part of its switch contacts made of material that is a conductor of electricity and that connects the switch contacts of the inertia element with one another.

9. An electric switch including: a first contact, a second contact which is movable with respect to the first contact, a pressure chamber, a flexible diaphragm across one end of the pressure chamber, means connecting the movable contact to the side of the diaphragm opposite the pressure chamber, the connecting means extending through an opening in the diaphragm, and a second flexible diaphragm on the pressure chamber side of the first flexible diaphragm, the second diaphragm being imperforate and extending across and radially beyond the connecting means and said opening and being secured to the first diaphragm beyond said connecting means and said opening for preventing leakage through any clearance around the connecting means at said opening.

10. The electric switch described in claim 9 characterized by the pressure chamber being of round crosssection and having peripheral edge portions for clamping circumferential edges of the diaphragms, both of the diaphragms having their circumferential edges clamped between said edge portions of the chamber, and the second diaphragm being secured to the first diaphragm by the clamping together of the circumferential edges of the diaphragms, the second diaphragm being thinner and more flexible than the first diaphragm and being unconnected to the first diaphragm except at said circumferential edges.

References Cited UNITED STATES PATENTS 4/1941 Barry 7351 5/1961 McCabe et al. 2006l.45 XR U.S. Cl. X.R. 20083 

